Electric-voltage regulator.



F. R. M. OUTOHEON. ELECTRIC VOLTAGE REGULATOR.

APPLICATION FILED AUG. 22, 1908.

Patented Jan. 18, 1910.

FREDERICK R. M. CUTCHEON, OF ST. PAUL, MINNESOTA.

ELECTRIC-VOLTAGE REGULATOR.

Specification of Letters Patent. Patented Jan. 18, 1910.

Application filed August 22, 1908. Serial No. 449,846.

To all whom it may concern:

Be it known that I, FREDERICK R. M. CUTCIIEON, a citizen of the UnitedStates, residing at St. Paul, in the county of Ramsey and State ofMinnesota, have invented certain new and useful Improvements inElectric-Voltage Regulators; and I do hereby declare the following to bea full, clear, and exact description of the invention, such as willenable others skilled in the art to which it appertains to make and usethe same.

My invention has for its especial object to provide an improved voltageregulator, of

simple construction and small cost, and to,

this end it consists of the novel devices and combinations of devices,hereinafter described and defined in the claims.

There is no practical automatic regulator to regulate the voltage of theindividual consumer, compensating for the variations in line loss in thedistributing mains and house wiring. This is one of the most diflicultproblems with which the central station on gineer has to contend. It ispossible, with the existing station regulators, to adjust the regulation so that the consumer having the low est voltage will getsatisfactory regulation and sufficient voltage; but if this is donethere will always be some consumers whose voltage is too high. Thenatural and simplest method of reducing this voltage is to insert aresistance in the consumers service wires. However, we are thenconfronted with this dilemma, that if a few lights only are turned on, aconsiderable resistance is required to cut the voltage down to thenormal lamp voltage, while if this resistance is used when a largenumber of lamps are turned on, the voltage will be cut down too far. Itis therefore necessary to provide a resistance which will decrease asthe current flowing increases. This may be done throughrheostats ofeither the wire Wound or liquid type operated either by magneticsolenoids or small motors, but such devices 'are expensive in first costand maintenance and prone to get out of order.

The device which I have devised to accomplish this purpose consists of anumber of contact resistances composed preferably of elements havingdifferent coefficients of ex pansion, such for example as brass andcarbon rings, cylinders or disks, alternated in a pile and arranged soas to be held loosely in contact, when cold, and to be forced intocontact with increasing force, as the temperature thereof is increased.Otherwise stated, the contact or resistance members, when looselyengaged, have imperfect contact, but this contact is made more perfectby increasing pressure, and of course the resistance to the currentdecreases as the contacts become more perfect.

When current is passed through the pile, heat is generated, at eachcontact, as well as vin the conductors themselves, and this heat causesthe brass contacts to expand, while the iron frame not being exposeddirectly to the heat, remains cooler, and having a lower coefiicient ofexpansion, does not expand nearly as much as the brass. Consequently acertain pressure will be caused between the carbon and brass contacts,and this pressure is proportional to or varies with the amount ofexpansion, which, in turn, varies with the temperature, and thetemperature rises or falls as'the current increases or decreases. Theresistance of thepile decreases as the expanding pressure increases;hence, the

more current there is flowing through the pile, the smaller theresistance of the pile will be, which is the characteristic previouslyspecified for a resistance to be used to absorb excess voltage on anindividual service.

With the pile constructed as above described, the contacts being loose,if a considerable load is switched on, there might be an arc ofdestructive character started between the contacts. To avoid this, I usean auxiliary fixed resistance, in multiple with the pile, and of suchdimensions that the current passing through it can not supply more thanthe minimum allowable voltage to the wiring system, and so arranged thatthe heat developed in the auxiliary resistance will assi st in producingexpansion of the brass contacts. The pile will then pass enoughadditional current to raise the voltage to approximately the normalamount.

Any metal having ahigh co-efficicnt of expansion and a comparativelyhigh melting point- Inay be substituted for brass in the above device,and any metal with a low coefficient of expansion and great tensilestrength may be substituted for iron in the so called frame.

The improved voltage regulator in one form which in practice has beenfound efiicient for the purposes had in view is illustrated in theaccompanying drawing, wherein like characters indicate like partsthroughout the several views. 7

Icferring to the drawings: Figure 1 is a plan view of the improvedregulator. Fig. 2 is a vertical section taken on the line in a of Fig.1; and Fig. 3 is a horizontal section taken on the line :0 00 of Fig.

In this arrangement, the alternated metal and carbon contact members ofthe pile are in the form of rings indicated, respectively,

by the mnnerals 1 and 2, and these are placed around an insulatingsleeve 8 throu h which an iron tube 4: is passed. The en s of the tube 4are threaded and nuts 5 work thereon with insulating disks 6 beinginterposed between the said nuts and the adjacent end members of themetal contact rings 1. The metal contact rings 1 are preferably formedwith projecting heat radiating ribs 7 for the purpose of adapting thepile to cool rapidly. The end members of the metal contact rings 1 areprovided with binding screws 8 to one of which one of the consumersservice wires 9 is connected, the other wire 9 being connected to thehouse wiring.

The auxiliary resistance, above referred to, is, in this construction,in the form of a coiled iron wire 10 located within but insulated fromthe metal tube 4, with its ends connected to the two end members of themetal contact rings 1. In Fig. 2, the ends of the tube at are shown asplugged, by a filling of cement or plaster paris which, in practice,would be preferably made to completely fill the tube a, so as to therebyform a ood insulation between the said tube and the said auxiliaryresistance wire 10. In the above described arrangement, the metal tube tand nuts 5 constitute'the frame for holding the contact members of thepile together and for limiting or resisting the expansion of the contactmembers 7 and 2, and hence, causing the same to press together underincreased force and increasing temperature so as to thereby give a morecomplete contact and, hence, a decreasing resistance under increasingcurrent flow and consequent increased heat action and expansion of thesaid contact members. The auxiliary resistance 10 being inclosed willraise the temperature rapidly at starting and bring the pile quicklyintoaction.

In practice, it may be desirable to use more or less fixed resistance inseries with the pile. so that the drop of potential through theregulator will not be too small at full load.

What I claim. is

1. A voltage regulator com rising a plurality of contiguous expansi 1econductor members normally having imperfect contact with one another,and means for opposing the expansion of said members, whereby anincrease in temperature due to the current tlow through said conductormembers will efi'cct a corresponding increase in the contact pressurebetween the several members and a decrease in the electrical resistanceof the series.

2. In a voltage regulator, the combination with a multiplicity ofloosely engaged expansible contact members connected in a supplycircuit. and normally having imperfect contact, of a frame for resistingexpan' sion of the said contact members, whereby under increasingcurrent flow therethrough, said contact members will be expanded andforced into engagement under increased pressure, thereby rendering thecontact between said members more perfect and decreasing the electricalresistance.

3. In a voltage regulator, the combination with a multiplicity ofcontacts connected into an electrical supply circuit and arranged to beengaged under increasing pressure, when expanded, and to thereby afforda decreasing electrical resistance under increasing current flowtherethrough, and an auxiliary resistance connected in multiple withsaid contacts for insuring the proper current flow when the saidcontacts are cold and loosely engaged.

t. In a voltage regulator, the combina tion with a multiplicity ofloosely engaged contacts connected in a supply-circuit, of a frame forresisting expansion of said contacts, whereby under increasing currentflow therethrough, said contacts will be engaged under increasingpressure and thereby afford a decreasing electrical resistance, and anauxiliary electrical resistance connected in multiple with saidcontacts, for insuring a proper current flow when said contacts are coldand loosely engaged.

5. In avoltage regulator, the combination with a multiplicity ofalternated carbon and metal contacts connected in a supply circuit, of aframe for resisting expansion of said contacts. whereby, underincreasing current flow therethrough, said contacts will be engagedunder increasing pressure and thereby afford a decreasing electricalresistance, and an auxiliary resistance connected in multiple with saidcontacts for insuring the proper current flow when said contacts arecold and loosely engaged.

6. In a voltage regulator, the combination with a metal tube, of amultiplicity of contact rings, surrounding but insulated from said tube,and loosely enga ed abutments. such as nuts on the ends of the saidtube, for resisting expansion of the said contact rings, circuitconnections to the end members of said contact rings, and an auxiliaryresistance wire located within said tube and connected in said circuit,in multiple with said contactrings, for insuring proper current flow,when said contacts are cold.

7. A voltage regulator comprising a series of contiguous conductormembers having different coefiicients of expansion and being normally inimperfect contact with one another, and means for 0 posing theexpancircuit, of a frame for resisting expansion of said contacts,whereby, under lncreasmg current flow therethrough, said contacts will15 be engaged under increasing pressure and thereby afford a decreasingelectrical resistance in presence of two Witnesses. K

FREDERICK R. M. CUTOHEON. Witnesses:

D. W. BURGESS, H. F; SUTMAR.

In testimony whereof I aflix my signature

